This invention relates to laser devices and particularly, although not exclusively, to those which use as lasing media materials which are normally either solid or liquid at room temperature and which lase in the gas or vapor phase.
For any one material used as a looing medium, there is usually one frequency output which is the easiest to obtain and which in operation usually predominates. However, it is often required that a laser should be able to produce two or more outputs of different wavelengths.
Combining two materials in an admixture and using them together so that both materials receive the same excitation, does not work satisfactorily because each material requires different optimum conditions. Often operating in this manner causes one material adversely to affect the excitation of emission of the other.